Injection press for denture materials



March 11, 1958 E. H. LOCHRIIDGE 7 2,825,931

INJECTION PRESS FOR DENTURE MATERIALS Filed Feb. 15. I954 EZW/N E LOCHQ/DGE,

INVENTOR.

Jrraeus).

Patented Mar. 11, 1958 ice INJECTIQN rnnss non nnNrunn MArEmALs Edwin H. Lochridge, Glendale, Calif., assignor to Dental Perfection Company, Glendale, Califi, a corporation of California Application February 15, 1954, Serial No. 410,406

8 Claims. (Cl. IS-3d) This invention has to do with heated plunger-type presses adaptable for the plasticizing, by heating, of normally rigid materials, and for the forced injection of the heated material into a mold. Because the invention has been developed with the particular objectives of improving upon heated injection presses for plasticizing and injecting dental resinous materials into molds, e. g. acrylic or other appropriate synthetic resins into denture molds, the invention will be described in this typical adaptation.

In its more specific aspects the invention is directed to improvements in a type of press comprising a case structure which includes a heating tube suitably positioned and which for reference convenience may be described as vertically extending, and a surrounding heating element, the tube containing a compression barrel extending and having below the case an injection outlet, the upper end of the tube receiving a plunger which is mechanically actuable to compress and discharge the heated resin from the barrel. The customary practice is to charge into the barrel, heat and inject in any one operation that quantity of resin to be used in the formation of a single denture.

These denture resins, while all generally pinkish, may require different color shadings in different instances, and consequently it is commonly necessary to follow the heating and injection of a given resin with another having a different shade. However, in order to assure an exact and uniform coloring of a batch, it is essential that all of a preceding batch of different coloring be removed from the barrel. Heretofore the barrel has been made, in elfect, an integral part of the case structure, and consequently it could only be cleaned While in place within the case. Now changing of the barrel presents difiiculties in that while the resin may be removed most readily by solvent, the temperature of the barrel at the end of a heating, compression and injection operation, and for a considerable length of time thereafter, is so high as to prevent the use of solvent. Accordingly, solvent cleaning would necessitate idling the equipment throughout a prolonged cooling period. a common practice has been to put through the barrel a quantity of the resin having the color of the intended next denture, but which is used only for cleaning out and removing from the barrel the residue of the preceding batch. This practice, while having the advantages of reducing delay in successive uses of the equipment, involves waste of resin to be used merely for cleaning the barrel.

The present invention has for its general object to facilitate and expedite cleaning and successive uses of the equipment, by removably securing the compression barrel in the case heating tube, to the end that following one use of the equipment it may be quickly reconditioned for In order to avoid such delay,

til

successive use without occasion for resin discoloration or wastage of the resin. In accordance with the invention, the compression barrel is detachably secured to the case structure within and in heat transferring relation with the heating tube, in a manner such that following injection of the resin into a denture mold, the barrel may be quickly and easily removed and replaced with a clean barrel readily for reception and heating of the next resin batch. The temperature condition of the heating element and tube does not require change during the barrel substitution. The removed barrel may be water cooled very quickly to a temperature permitting cleaning by solvents, such cleaning being greatly facilitated by the accessibility to all parts of the barrel apart from the machine.

structurally, the invention contemplates mounting the lower portion of the barrel carrying the plug or valve, within a collar stationarily carried by the case structure, and preferably secured to the lower end of the heating tube. Recognizing that variations may be made in the specific form of the barrel attachment, it is preferred to so relate the lower end of the barrel to the supporting collar that the valve stem is extended through the collar and requires withdrawal in order that the barrel may be dropped down through the collar.

All the various features and objects of the invention, as well as the details of an illustrative embodiment, will be understood more clearly from the following description of the accompanying drawing, in which:

Fig. l is a View showing the injection press in front elevation, certain parts being broken away to reveal the interior construction;

Fig. 2 is an enlarged cross-sectional view showing the valve and barrel assembly at the bottom of the case; and

Fig. 3 is a cross-section taken on broken line 3-3 of Fig. 2.

While it is contemplated that the general form and structure of those parts of the press assembly which mount the compression element or plunger and the case and its directly associated part, may take any of various forms and designs, the particular press structure shown in Fig. 1 may be regarded as typical and illustrative ofa press which in practical operation has been found to give good results.

First in reference to the frame structure of the press, the latter comprises a base 10 from which rises a pair of extended parallel rods or bolts 11 affixed at their upper ends between nuts 12 to a cross head 13. Also extending between and adjustably fixed to the rods, as by insertion of screws, bolts or other fasteners within registerable openings 14 and 15, is a support 16, the upper surface of which has a cavity 17 for reception of the resin to be heated, as will be later explained. To the bottom of the support 16 is a case assembly, generally indicated at 18, comprising a metal shell 19 containing a tube 20 which projects below the bottom of the shell, see Fig. 2, and is surrounded inside the base by an appropriate electrical heating element diagrammatically indicated at 21. The case may carry appropriate controls such as settable temperature and thermostatic regulators, the dials for which are indicated at 22 and 23. Thus the heating element 21., being in direct heat transferring relation to the tube 2%, may be so controlled as to supply heat transmitted to the tube and the later described barrel to the resin, at levels suflicient for plasticizing of the resin.

The tube 20 contains a tubular barrel 24 extending down through the tube and containing at its lower end a reduced diameter discharge bore 25. The rods 11 guide a base or platform 26 which may be raised and lowered by the nut and screw assembly at 27 to elevate a denture mold, generally indicated at 28, against the tapered nozzle end 2% of the barrel for injection of the resin into the mold, and to drop the mold away after the denture is completed. As Fig. 2 shows, the tapered end of the barrel may be received within a correspondingly shaped recess 30 in the mold to permit pressurized transfer of the resin from the barrel through opening 31 into the interior of the mold.

The resin, normally in a rigid or non-plastic state, filled into the barrel through its upper open end and then heated to a state of plasticity in the barrel, is compressible during the heating, if desired, and thereafter for injection into the mold 128, by a plunger 32 which may carry on its back face teeth 33 serving as a rack engaged with a gear on shaft 35 which is rotatable by hand wheel as to raise or lower the plunger.

Threaded on the bottom projecting end of the tube is a collar 37, the counterbore 38 of which contains a ring 39 which may shoulder against the lower end of the tube and which is releasably held in place within the collar by a pin 40 insertible and removable through opening 41 in the collar. A cylindrical cock or plug-type valve 42 containing an opening 43 corresponding in diameter to the barrel bore 25, extends diametrically through openings at 44 and 45 in the collar 37 and ring 39, the valve being removably retained within the sleeve by a split washer or ring 46. The valve carries a turning handle 49 and a pin 47 engageable against a stop 48 projecting from the collar 37, to arrest rotation of the valve in its closed Fig. 2 position.

In considering the operation of the press, we may assume that a batch of the resin has been heated to plastic condition in the barrel, with the valve 42 in closed position, and that thereafter the plunger has been forced down within the barrel to discharge the plastic resin through the open valve and injection end of the barrel into the mold 28. Some of the resin will of course remain in the barrel, and for reasons heretofore explained, it is desirable that in order for the press to be quickly available for a subsequent heating and molding operation, a thoroughly clean barrel be available. The removability of the barrel and its quick replaceability by a clean barrel assures tln's expeditious continuity of operation. When injection into the mold is completed, lock ring 46 is taken from the valve and the latter is removed from the collar and barrel assembly. The barrel 24- then may be dropped or forced down and out of the sleeve 29 for cleaning in openly accessible condition away from the press. A clean barrel is then put into the heating tube, the valve locking pin and lock ring reinserted, and the press is ready for another operating cycle.

I claim:

1. Au injection press of the character described comprising a vertically extending tubular sleeve, a case structure containing said sleeve and means for exteriorly heatin g the sleeve, a tubular barrel extending within the sleeve in heat transferring relation therewith and projecting from the lower end of the sleeve, means including a valve detachably securing said barrel to the sleeve. and case assembly so as to be removable from the sleeve with the valve carried by the lower portion of the barrel for opening and closing the discharge therefrom of heated plastic mate rial, and a compression plunger received within the top of the barrel.

2. An injection press of the character described comprising a vertically extending tubular sleeve, 2. case structure containing said sleeve and means for exteriorly heating the sleeve, a tubular barrel extending within the sleeve in heat transferring relation therewith and projecting from the lower end of the sleeve, means including a valve detachably securing said barrel to the bottom of the sleeve and case assembly so as to be removable downwardly from the sleeve with the valve carried by the lower portion of the barrel for opening and closing the discharge therefrom of heated plastic material, and a compression plunger received within the top of the barrel.

3. An injection press of the character described comprising a vertically extending tubular sleeve, 21 case structure containing said sleeve and means for exteriorly heating the sleeve, a tubular barrel extending within the sleeve in heat transferring relation therewith and projecting from the lower end of the sleeve, a collar carried by the bottom of the case and sleeve assembly and receiving therethrough the lower portion of said barrel, means including a valve releasably securing the barrel to said collar with the valve carried by the lower portion of the barrel for opening and closing the discharge therefrom of heated plastic material, and a compression plunger received within the top of the barrel.

4. An injection press of the character described comprising a vertically extending tubular sleeve, a case structure'containing said sleeve and means for exteriorly heating the sleeve, a tubular barrel extending Within the sleeve in heat transferring relation therewith and projecting from the lower end of the sleeve, a collar secured to the lower end of said sleeve and extending below the case to receive therethrough the lower portion of said barrel, means including a valve releasably securing the barrel to said collar with the valve carried by the lower portion of the barrel for opening and closing the discharge therefrom of heated plastic material, and a compression plunger received within the top of the barrel.

5. An injection press of the character described comprising a vertically extending tubular sleeve, a case structure containing said sleeve and means for exteriorly heating the sleeve, a tubular barrel extending within the sleeve in heat transferring relation therewith and projecting from the lower end of the sleeve, a collar carried by the bottom of the case and sleeve assembly and receiving the lower portion of said barrel, means including a rotatable plug valve releasably securing the barrel to said collar with the valve extending diametrically through a side of the collar and through the barrel for opening and closing the discharge therefrom of heated plastic material, and a compression plunger received within the top of the barrel.

6. An injection press of the character described comprising a vertically extending tubular sleeve, a case structure containing said sleeve and means for exteriorly heating the sleeve, a tubular barrel extending within the sleeve in heat transferring relation therewith and projecting from the lower end of the sleeve, a collar secured to the lower end of said sleeve and extending below the case to receive the lower portion of said barrel, means including a rotatable plug valve releasably securing the barrel to said collar with the valve extending diametrically through aside of the collar and through the barrel for opening and closing the discharge therefrom of heated plastic material, and a compression plunger received within the top of the barrel.

7. An injection press of the character described comprising a vertically extending tubular sleeve, a case structure containing said sleeve and means for exteriorly heating the sleeve, a tubular barrel extending within the sleeve in heat transferring relation therewith and projecting from the lower end of the sleeve, a collar secured to the lower end of said sleeve and extending below the case to receive the lower portion of said barrel, a barrel encircling ring inside and bearing upwardly against the collar, means including a rotatable plug valve releasably securing the ring to the barrel with the valve extending diametrically through a side of the collar and through said ring and the barrel, and a compression plunger received within the top of the barrel.

8. An injection press of the character described comprising a vertically extending tubular sleeve, a case structure containing said sleeve and meansfor exteriorly heat- 5 6 ing the sleeve, a tubular barrel extending within the by the valve to limit rotation thereof, and a compression sleeve in heat transferring relation therewith and proplunger received within the top of the barrel. jecting from the lower end of the sleeve, a collar secured to the lower end of said sleeve and extending below the References Cited in the file of thi patent case to receive the lower portion of said barrel, a barrel 5 encircling ring inside and bearing upwardly against the UNITED STATES PATENTS collar, means including a rotatable plug valve releasably 1,606,705 loannides Nov. 9, 1926 securing the ring to the barrel with the valve extending 2,414,948 Hermanns Jan. 28, 1947 diametrically through a side of the collar and through 2,573,805 Neustadter Nov. 6, 1951 said ring and the barrel, a stop on the collar engageable 10 

